Snippet

advent_of_code/2024_13.rb

Code:

# Advent of Code 2024, Day 13: Claw Contraption

# https://adventofcode.com/2024/day/13

require_relative './helpers.rb'

def find(ax, ay, bx, by, px, py)
  b = (py * ax - px * ay) / (by * ax - bx * ay).to_f
  a = b.is_i? ? (px - b * bx) / ax.to_f : 0
  a.is_i? && b.is_i? ? (a * 3 + b).to_i : 0
end

def part_one(rules)
  rules.sum { |r| find(*r) }
end

def part_two(rules)
  rules.sum { |r| find(*r[0, 4], r[4] + 10 ** 13, r[5] + 10 ** 13) }
end

def solve(data)
  rules = data.each_slice(4).map { |a, b, c, _| [
    a.split(/\+|\,|$/).select { |n| n.is_i? },
    b.split(/\+|\,|$/).select { |n| n.is_i? },
    c.split(/\=|\,|$/).select { |n| n.is_i? },
  ].flatten.map(&:to_i) }
  [part_one(rules), part_two(rules)]
end

puts solve(get_dataset(year: 2024, day: 13, type: 'example'))
puts solve(get_dataset(year: 2024, day: 13, type: 'example_2'))
puts solve(get_dataset(year: 2024, day: 13, type: 'input'))

Output:

480
875318608908
875318608908
0
29517
103570327981381